Safety-device-operating mechanism



April 28, 1931. .T. T. ALLEN ET AL SAFETY DEVICE OPERATING MECHANISM Filed Oct. 12. 1927 3 Sheets-Sheet 1 INVENTORS: i'zomas 2141:3012 film fiancLs/fdam;

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v ATORNIEY WITNESSES:

p l 28, 3 T. T, ALLEN ET AL 1,303,037

SAFETY DEVICE OPERATING MECHANISM Filed 9ct. 12, 1927 5 Sheets-Sheet 2 wnzvrsazra: INVENTORS:

Tflomas Z'AZZen (8.

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WM I ATTORNEY.

Patented Apr. 28, 1931 UNITED STATES moans? PATENT OFFICE THOMAS T. ALLEN AND JOHN FRANCIS ADAMS,

0F PHILADELPHIA, PENNSYLVANIA,

SYLVAKIA SAFETY-DEVIGE-OIPEBATNG MECHANISM Application filed October 12, 1927. Serial No. 225,807.

This invention relates to safety devices for motion picture projecting machines and particularly to mechanisms for operating such devices when the film breaks, slips, or moves substantially out of its normal path.

In the operation of motion picture projecting machines it frequently happens that the film is not uniformly fed under the aperture plate by the sprockets which engage the perforations in the sides-of the film and, consequently, the loop which is maintained above the aperture lengthened so as to pile up, or the loop ma be diminished until the film is torn or bro en. 1 .i

One of the most f uent causes of such a condition is torn per orations or s rocket holes in the sides of the film, althoug other conditions may contribute to the improper feeding of the film across the aperture so that the condition created thereby will not only cause improperv projection of the film images, but may create a, fire hazard, due tc a nonmovingportion of the film coming in direct contact with the rays from the arc.

Qne of the objects of this invention is to provide means whereby the excessive enlargement or diminution of the film loop will actuate mechanism which, in turn, will actuate the safety device for obstructing the rays from the arc.

Another object of the invention is to provide mechanisms which are directly operated bythe film for accomplishing the foregoing o ect.

According to the invention, the motion picture machine which is intended for projecting the images of a film has a loop formed in its film above the aperture plate, the machine is provided with a film guard upon which an'electrical switch is mounted, and the mechanism includes means for operating the switch when the loop is excessively enlarged, and mec nism for operating the switch when the cop is excessively diminished. y

The drawings illustrate an embodiment of the invention and its adaptability for operating a safety device for obstructing the light rays late is either greatly' from the are when the film loop is en larged or diminished and the views therein are as follows:

Figure 1 is a fragmentary side view of a motion picture projecting machine showing the improved with; certain standard parts of the machine being omitted and other parts broken away in order to expose parts necessary to the disclosure.

Figure 2 is same machine but viewing same from the opposite side; certain parts being omitted for a better understanding of the invention.

Figure 3 is a side view of a switch, used in mechanism associated therea fragmentary view of the connection with our invention, with the cover I of the switch casing removed.

Figure 4 a perspective view of the switch, actuator shown in Figures 1 and 2, and

' Figure 5 a wiring diagram and schematic drawing, showing the electrical connections of the various elements which constitute the automatic control apparatus with the invention incorporated therein.

Referring now more in detail to the drawings, 11 represents the upper magazine of a motion picture projecting machine having a reel 12 mounted therein from which film 13 is led between guide rollers 14, under a deflector roller 15 and over 16 with which it is held in contact by a roller 17. From the upper sprocket, the film is formed into a loop flanged roller 19 past the projection aperture to the intermittent sprocket (not shown) in the usual manner; loop 18 being accommodated by a guard 20 mounted on the gate 21. This is standard mechanism.

In applying our invention to a projecting machine, it is found advantageous to secure theupper sprocket 18 and directed by the the switch 22 to one side of loop guard 20 with A its shaft 23 extending above the path of film 13 and having fixed thereto a contact plate 2/ which is curved somewhat in the she of loop guard 20 and disposed in front 0 loop 18 and disposed within the I that, if film 13 should break, the token end of the film would strike contact plate 24 and actuate switch 22o It sometimes happens that, due to a defective film or other causes, the film is fed faster guard .so

by the intermittent sprocket than by sprocket 16 with the result that loop 18 is lost or eliminated and the film caused to tear or break. In order to prevent this, a screw 25, having a plain end 26, is substituted for the screw furnished with the machine and the actuator 27,

normally rests upon a bracket 30, and a bar 31 fixed in the depending arm of the actuator extends within the loop 18 parallel with the width of the film. The bar 31, which has its end bent for facilitating the threading of the film through the projectm ed to be engaged by the 18 is sufiicientl the actuator 2 against a finger 32 secured on the switch shaft 23. This finger is maintained against rotation on the said shaft by a set screw 33. Whenever loop 18 increases in size or the film breaks, the contact plate 24 will be engaged thereby and will rotate the shaft 23 to c ose the switchv22, or, ifthe loop 18 is sufficiently diminished, actuator 27 will engage finger 32 and close switch 22 which is .electrically connected into an automatic control system as will be hereinafter described. Tllie switch shaft 23 is rotatably mounted in t with a cam, 39 which engages a terminal 40 normally spaced from the other terminal 41; both terminals being preferably moilnted upon an insulating core 42 and connected to wires 43 and 44 forming parts of an eleclm whenever loop tric circuit which is closed at this point when cam 39 rotates and forces terminal 40 against terminal 41. I a

Our improved switch is here shown in con- Junction with an automatic control apparatus having a main unit or safety device 48 adapted to be mounted upon the cone 49 of the lamp house used with a motion picture pro ecting machine. Safety device 48 is'provided with a dowser .50 adapted to swing in front of (zone 49 and intercept the rays of' light passing through the film but normally held out of light obstructing position by a trip arm 51 engaging a catch (not shown) secured to the shaft 52 on which dows'er 50 is attached.

A crank 53 is rockably mounted in the casing 54 below trip arm 51 and adapted to actuate same and release dowser 50 when its a other end is engaged by a plunger 55 which is normally held away from crank 53 against the action of a spring 56 by a solenoid 57. A spring bearing 58, having one end secured to casing 54 and its other end supported by a cam 59 fixed on shaft 52, supports a mercury switch 60so that, when dowser 5O ,falls, cam 59 will be rotated and allow spring bearmachine, is adapt-' diminished and it will swing' e casing 38 of switch 22 and provided .noid 5 ing 58 to tilt switch 60 and break the electric circuit into which it is connected.

Power for operating the projecting machine and the been shown as being derived from a power line A-B through a switch 63 which has one of its poles connected by a wire 64 to one side of the motor M, which drives the projecting machine, and its other pole connected by wire 65 to one side of a rela 66 having its other side connected to the other side of motor M b a wire 67, so that, when relay 66 is close motor M may be supplied with power.

One end of the winding of relay 66 is connected to wire 64 by a wire 68 and its other end is connected by wire 69 to one of the terminals of mercury switch 60. The other terminal of mercury switch 60 is connected by wire 70 to a junction 71 which is connected by a wire 72 to wire 65 so that, when switch 60 is closed, the winding of rela 66 will be energized and the motor circuit eld closed.

One end of the winding of solenoid 57 is connected by a wire 73 to junction 71 and the other end of its winding connected by a wire 74 to a wire 75 which is connected to a resistance 76connected to wire 67 by wire 77. When the motor circuitis complete and switch60 closed solenoid 57 will be energized by a current owin from wire 67 through wire 77, resistance 6, wire 75, wire 74, junction 71, wire 70, switch 60, wire 69, the winding of relay 66 and wire 68 to wire 64 so that plunger 55 is held awayfrom crank 53 when the circuits are closed.

The other end of wire 75 is connected to one terminal of a centrifugal switch 78 whose other terminal is connected to junction 71 by a wire 79. Switch 22 is connected to wire 75 by wire 44 and to wire 79 by wire 43, thus puttin it in parallel with switch 78 and sole- 7 while a second film actuated switch 80 is connected in parallel therewith between wires 75 and 79 as diagrammatically shdwn.

Switch 80 is dispose below the projection aperture of the projecting machine and 1s adapted to be actuated if the film should automatic control device has the winding of the solenoid, wire 73, v

breakor tear at this point or between it and 7 switch 22. Centrifugal switch 78 is mechanically connected to a rotating art of the projecting machine and adapte to .close whenever the speed of the film falls below a certain number of feet per minute. Switches 22,78 and 80 being connected in parallel, the closing of any one of them will cause the actuation of safety device 48 b allowing a rush of current to flow throng wire 75 and the switch involved to junction 71, thus short-circuiting solenoid 57 and depriving sameof a portion of thepower required by it to hold plunger 55 against the action of spring 56 and allowing spring 56 to film, rotate cam 59 and tilt switch 60, reakthe circuit at this point and deenergizing relay 66 and allowing the relay to open and deprive the motor of its power.

It is, of course, understood that the safety device operating mechanisms illustrated may be. modified and changed in various ways without departing from the invention herein set forth and hereafter claimed. 3

We claim 1. In a motion picture machine for projecting images from a film wherein the film is provided with a loop, means for making and reaking an electric circuit including a switch having a shaft, spring terminals, and a cam on the shaft adapted to force the terminals together; a curved plate fixed on the shaft and disposed adjacent the outside of the loop; a finger fixed on the shaft; and an actuator extending inside the loop and adapted to engage the finger.

2. In a motion picture machine for projecting images from a film wherein the film in provided with a 100 said machine havin a safety device inclu inga dowser adapte to operate to obstruct the light rays upon the closing of an electric circuit, a switch having cam and force said terminals together when thefilm' engages said bar.

In testimony whereof we have signed our names to this s ecification.

T OMAS T. ALLEN. J OHN FRANCIS ADAMS.

a cam mounted on a shaft or closing switch terminals, a plate fixed on said shaft and disposed without said loop', whereby. said switch is operated by the excessive enlargement of said loo to. close said circuit, a finger'on said sha and an actuator dis osed within said loop for engaging said whereby said switch is operated by the excessive diminution of said loop to close said circuit.

3. In a motion picture machine for projecting images from a film wherein the film is provided with a loop, means for making and breaking an electric circuit including a switch having a shaft, spring terminals, and

p a cam, on the shaft adapted to force the terminals together,

"is provided with a loop, including a switch a plate fixed on the shaft to rotatably operate the cam shaft upon the enlargement of the loop, a finger fixed on the shaft, and an actuator extending inside the loop and adapted to engage the finger.

\ 4. In a motion picture. machine for projecting images from a film wherein the-film an electric circuit for making and breaking the said circuit, said switch having a shaft, spring terminals normally separated and a cam on the shaft adapted to force'the terminals together, a curved plate on the shaft to operate the switch upon enlargement of said loop, a finger fixed on the shaft, and a pivotally mounted actuatorhaving a bar for engagement by the film, said actuator bein" adapted to engage said finger to operate said ger 

